This article is from the WSSF 2009 AFRMA Rat & Mouse Tales news-magazine.
From Pathology of Laboratory Rodents & Rabbits, Second Edition, Dean H. Percy and Stephen W. Barthold.
Did You Know? Rat and mouse bones lack Haversian systems (one of the cylindrical units of which compact bone is made). Adult rats, particularly males of some strains, continue to grow, and epiphyseal ossification is not complete until after 1 year of age. Hematopoiesis (the process of production of blood cells and platelets which continues throughout life, replacing aged cells) remains active in long bones throughout life.